A. Field of the Invention
The present invention relates to a new and improved muffler for a tool employed for driving fasteners into a workpiece.
B. Description of the Prior Art
Most prior art tools employed for driving fasteners into a workpiece are powered by compressed fluids such as pressurized air. The typical prior art tool includes a nose portion within which a piston is mounted and secured to a driver for driving fasteners. Compressed air is introduced above the piston to power the driver through a driving stoke. The air below the piston during the driving stroke is not exhausted but is contained within a reservoir and compressed under the influence of the downward moving piston. At the completion of the downward stroke of the driver, the air forced into the reservoir is released allowing this air to return the driver and piston to the original position. There is, however, an exhaust port located at the upper end of the piston chamber of the tool that allows escape of the air above the piston to pass to the atmosphere. A muffler may be included in this upper exhaust port that is a porous bronze or a beaded plastic member through which the air passes to muffle the noise.
In such prior art tools, there is no need for a lower muffler to muffle the noise created by, for example, the engagement of the piston with a bumper located at the lower end of the nose portion and The noise created by the compressed air being compressed by the downward moving piston and driver during a driving stroke; however, there are prior art tools that do not employ the air below the piston to return the driver to the static position. These latter tools exhaust the air below the piston to the atmosphere.
The typical prior art muffler employed in the upper exhaust ports allow air to pass into the center of the muffler and to dispense or disburse radially outward through the muffler element. It is desirable to employ a muffler in the exhaust of tools exhausting air below the piston and to employ a muffler that is an improvement of the prior art muffler employed in the upper exhaust ports of prior art tools.